RESUMO
Estimation of biomechanical parameters of soft tissues from noninvasive measurements has clinical significance in patient-specific modeling and disease diagnosis. In this work, we present a quasi-nonlinear method that is used to estimate the elastic moduli of the human gallbladder wall. A forward approach based on a transversely isotropic membrane material model is used, and an inverse iteration is carried out to determine the elastic moduli in the circumferential and longitudinal directions between two successive ultrasound images of gallbladder. The results demonstrate that the human gallbladder behaves in an anisotropic manner, and constitutive models need to incorporate this. The estimated moduli are also nonlinear and patient dependent. Importantly, the peak stress predicted here differs from the earlier estimate from linear membrane theory. As the peak stress inside the gallbladder wall has been found to strongly correlate with acalculous gallbladder pain, reliable mechanical modeling for gallbladder tissue is crucial if this information is to be used in clinical diagnosis.
Assuntos
Módulo de Elasticidade , Técnicas de Imagem por Elasticidade/métodos , Vesícula Biliar/diagnóstico por imagem , Dinâmica não Linear , Anisotropia , Fenômenos Biomecânicos , Análise de Elementos Finitos , Vesícula Biliar/fisiologia , Esvaziamento da Vesícula Biliar , Humanos , Estresse MecânicoRESUMO
This paper studies human gallbladder (GB) smooth muscle contractions. A two-state cross-bridge model was used to estimate the apparent attachment and detachment rate constants, as well as increased Ca2+ concentration from the peak active stress during the isometric contraction. The active stress was computed from a mechanical model based entirely on non-invasive routine ultrasound scans. In the two-state cross-bridge model, the two apparent rate constants, representing the total attached/detached cross-bridges, respectively, were estimated using active stress prediction for 51 subjects undergoing cholecystokinin-provocation test, together with estimates from the four-state cross-bridge model for a swine carotid, bovine tracheal and guinea pig GB smooth muscles. The study suggests that the apparent rate constants should be patient-specific, i.e. patients with a lower stress level are characterized by smaller apparent rate constants. In other words, the diseased GB may need to develop fast cycling cross-bridges to compensate in the emptying process. This is a first step towards more quantitative and non-invasive measures of GB pain, and may provide useful insight in understanding GB motility and developing effective drug treatments.
Assuntos
Vesícula Biliar/metabolismo , Músculo Liso/metabolismo , Cálcio/metabolismo , Colecistocinina/metabolismo , Humanos , Cinética , Modelos Biológicos , Contração MuscularRESUMO
AIM: Current classification systems of large bowel cancer only refer to metastatic disease as M0, M1 or Mx. Recurrent colorectal cancer primarily occurs in the liver, lungs, nodes or peritoneum. The management of each of these sites of recurrence has made significant advances and each is a subspecialty in its own right. The aim of this paper was to devise a classification system which accurately describes the site and extent of metastatic spread. METHOD: An amendment of the current system is proposed in which liver, lung and peritoneal metastases are annotated by 'Liv 0,1', 'Pul 0,1' and 'Per 0,1' in describing the primary presentation. These are then subclassified, taking into account the chronology, size, number and geographical distribution of metastatic disease or logoregional recurrence and its K-Ras status. CONCLUSION: This discussion document proposes a classification system which is logical and simple to use. We plan to validate it prospectively.
Assuntos
Neoplasias Colorretais/patologia , Neoplasias Hepáticas/classificação , Neoplasias Pulmonares/classificação , Recidiva Local de Neoplasia/classificação , Estadiamento de Neoplasias , Neoplasias Peritoneais/classificação , Humanos , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/secundário , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/secundário , Metástase Linfática , Neoplasias Peritoneais/patologia , Neoplasias Peritoneais/secundárioRESUMO
BACKGROUND: We have previously shown that in a randomized comparison of laparoscopic (LC) versus small incision (SC) cholecystectomy, postoperative hospital stay is comparable. This randomized prospective study compares the postoperative pain, analgesic and antiemetic consumption, perceived health, and metabolic and respiratory responses after these two procedures. METHODS: Two hundred patients were recruited; postoperative stay, pain scores, analgesic and antiemetic consumption were recorded. Nottingham Health Profile questionnaires were completed by a subgroup of 100 patients, and the metabolic and respiratory responses were also compared in a further subgroup of 20 patients. RESULTS: Pain scores in both groups were low. LC, however, was associated with lower postoperative pain scores and analgesic requirements compared with SC, but the antiemetic requirements were greater after LC. The duration of hospital stay and the perceived health after operation were the same in both groups, and both procedures were associated with a similar reduction of respiratory function. Twenty-four hours after operation the inflammatory (C-reactive protein, CRP) response to LC (22 +/- 20 mg/L) was significantly lower than after SC (68 +/- 30 mg/L), but the neuroendocrine (cortisol) response was similar (LC, 475 +/- 335 nmol/L, compared with SC, 710 +/- 410 nmol/L). Independent of the technique used, the duration of postoperative hospital stay correlated significantly with the magnitude of both the 24-hour postoperative cortisol and CRP responses (cortisol: rs = 0.678, p < 0.001; CRP: rs = 0.566, p = 0.011). CONCLUSIONS: LC appears to be associated with less tissue destruction and pain than SC, but this did not confer any advantage in the degree of postoperative respiratory impairment, length of hospital stay, or postoperative perceived health. The neuroendocrine component of the metabolic response evoked by each procedure was similar and had a significant correlation to patient's postoperative hospital stay. This finding may explain the similar postoperative recovery after LC and SC.
Assuntos
Atitude Frente a Saúde , Glicemia/metabolismo , Colecistectomia Laparoscópica , Colecistectomia , Indicadores Básicos de Saúde , Dor Pós-Operatória , Testes de Função Respiratória , Adulto , Idoso , Analgésicos/uso terapêutico , Antieméticos/uso terapêutico , Proteína C-Reativa/análise , Método Duplo-Cego , Emoções , Feminino , Humanos , Hidrocortisona/sangue , Inflamação , Tempo de Internação , Masculino , Pessoa de Meia-Idade , Medição da Dor , Dor Pós-Operatória/tratamento farmacológico , Estudos ProspectivosRESUMO
BACKGROUND: Symptomatic gallstones in patients who are at high risk from or who wish to avoid anesthesia may be difficult to treat, especially if the gallstones are unsuitable for oral dissolution or lithotripsy. We describe our experience with a minimally invasive surgical method of gallstone extraction under thoracic epidural or intercostal anesthesia. STUDY DESIGN: Eight-one patients who were either at high risk from or did not wish to undergo general anesthesia or those who wished to conserve their gallbladder underwent percutaneous cholecystolithotomy with a modified cholecystoscope. Of these patients, 63 (78 percent) were in American Society of Anesthesiology grades III and IV and 28 (35 percent) had thick-walled, diseased gallbladders. RESULTS: Gallstones were completely cleared in 66 (81 percent) patients and complete symptom relief was obtained in more than 95 percent of these patients. There were no deaths or serious complications. CONCLUSIONS: Percutaneous cholecystolithotomy under regional anesthesia is an effective means of gallstone treatment in selected high-risk patients.
Assuntos
Colelitíase/cirurgia , Endoscopia do Sistema Digestório/instrumentação , Adulto , Idoso , Idoso de 80 Anos ou mais , Colecistectomia , Colelitíase/fisiopatologia , Feminino , Esvaziamento da Vesícula Biliar , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
BACKGROUND: The currently accepted hypothesis to explain acalculous gallbladder pain is the lack of contractile co-ordination between the body and neck. We have previously shown that bethanechol, a muscarinic stimulant causes differential stimulation of these two regions. AIM: To evaluate the reliability of bethanechol-induced gallbladder contraction in predicting symptom relief after cholecystectomy in patients with acalculous gallbladder disease. METHODS: Fifty-one patients underwent a bethanechol provocation test together with serial ultrasound to determine gallbladder emptying. McGill pain questionnaires were completed, and patients positive for pain (bethanechol provocation test +ve) were offered cholecystectomy, and patients negative for pain (bethanechol provocation test -ve) were reassessed at 6 months and offered cholecystectomy if symptoms persisted. All patients answered pain questionnaires either 6 months after surgery or as follow-up. RESULTS: There was no difference in the percentage of gallbladder emptying between the bethanechol provocation test +ve and bethanechol provocation test -ve groups. Fifty-three percent of bethanechol provocation test +ve patients and 54% of bethanechol provocation test -ve patients still remained symptomatic 6 months after surgery. Conclusion. Gallbladder pain provoked by bethanechol does not predict symptom relief after cholecystectomy.
Assuntos
Betanecol/farmacologia , Doenças da Vesícula Biliar/cirurgia , Dor/prevenção & controle , Adulto , Idoso , Betanecol/uso terapêutico , Colecistectomia , Feminino , Seguimentos , Doenças da Vesícula Biliar/complicações , Doenças da Vesícula Biliar/fisiopatologia , Humanos , Masculino , Pessoa de Meia-Idade , Agonistas Muscarínicos/farmacologia , Agonistas Muscarínicos/uso terapêutico , Dor/etiologia , Parassimpatomiméticos/farmacologia , Parassimpatomiméticos/uso terapêutico , Resultado do TratamentoRESUMO
A new simulator specifically designed for practising techniques in laparoscopic cholecystectomy is described. The simulator is inexpensive and utilises pig gallbladders. It allows a surgeon to practice without the need for assistance.
Assuntos
Educação Médica Continuada , Animais , Procedimentos Cirúrgicos Operatórios , Suínos , Materiais de EnsinoRESUMO
Inverse estimation of biomechanical parameters of soft tissues from non-invasive measurements has clinical significance in patient-specific modelling and disease diagnosis. In this paper, we propose a fully nonlinear approach to estimate the mechanical properties of the human gallbladder wall muscles from in vivo ultrasound images. The iteration method consists of a forward approach, in which the constitutive equation is based on a modified Hozapfel-Gasser-Ogden law initially developed for arteries. Five constitutive parameters describing the two orthogonal families of fibres and the matrix material are determined by comparing the computed displacements with medical images. The optimisation process is carried out using the MATLAB toolbox, a Python code, and the ABAQUS solver. The proposed method is validated with published artery data and subsequently applied to ten human gallbladder samples. Results show that the human gallbladder wall is anisotropic during the passive refilling phase, and that the peak stress is 1.6 times greater than that calculated using linear mechanics. This discrepancy arises because the wall thickness reduces by 1.6 times during the deformation, which is not predicted by conventional linear elasticity. If the change of wall thickness is accounted for, then the linear model can used to predict the gallbladder stress and its correlation with pain. This work provides further understanding of the nonlinear characteristics of human gallbladder.
Assuntos
Bile/metabolismo , Esvaziamento da Vesícula Biliar/fisiologia , Vesícula Biliar/fisiologia , Modelos Biológicos , Anisotropia , Simulação por Computador , Módulo de Elasticidade/fisiologia , Humanos , Resistência à Tração/fisiologiaRESUMO
INTRODUCTION: The aim of this study was to evaluate the sensitivity of magnetic resonance imaging (MRI) in the detection of colorectal liver metastases. PATIENTS AND METHODS: Pre-operative MRI scanning of the liver was performed by a single radiologist and the size and number of definite liver metastases were recorded. Patients then underwent hepatectomy with routine intra-operative ultrasonography (IOUS) and resected specimens were sent for histopathology. Pathology findings were compared with those of MRI scans to determine the sensitivity of this imaging modality. Exclusions were patients undergoing hepatic resection more than 4 weeks after the MRI scan, those undergoing chemotherapy at the time of the scan, and those with conglomerate unilobar metastases. RESULTS: Complete data were available for 84 patients. There was total agreement between MRI, IOUS and histology in 79 patients (101 metastases). MRI missed 5 metastases in 5 patients that were found on IOUS (or palpation of superficial lesions) and subsequently confirmed by histological examination. These measured 5 mm or less (4 patients) and 7 mm (one patient). The sensitivity of MRI in the detection of colorectal liver metastases was thus 94% for all lesions and 100% for lesions 1 cm or larger in diameter. CONCLUSIONS: MRI of the liver is a non-invasive technique with an extremely high degree of sensitivity in the detection of colorectal liver metastases and should be considered as the 'gold standard' in the pre-operative imaging of these patients.
Assuntos
Neoplasias Colorretais , Neoplasias Hepáticas/patologia , Imageamento por Ressonância Magnética/normas , Idoso , Idoso de 80 Anos ou mais , Feminino , Hepatectomia/métodos , Humanos , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/secundário , Masculino , Pessoa de Meia-Idade , Cuidados Pós-Operatórios/métodos , Cuidados Pré-Operatórios/métodos , Sensibilidade e Especificidade , UltrassonografiaRESUMO
BACKGROUND: The common hepatic duct (CHD) is commonly believed to dilate after cholecystectomy but previous studies have either not measured CHD diameter preoperatively or the follow up period is short. AIMS: To measure CHD diameter before and after cholecystectomy. METHODS: Patients undergoing (open) cholecystectomy and operative cholangiography had ultrasonographic measurement of CHD diameter before, and three and six months, and one and five years after cholecystectomy. The normal duct diameter was considered to be 5 mm or less, with an observer error of +/-1 mm. RESULTS: Fifty nine patients with normal diameter ducts were studied. The majority (more than 95%) of patients did not have a dilatation of the CHD beyond 6 mm after cholecystectomy. The CHD appeared to increase as well as decrease with an overall trend towards a minor increase at five years. This was not statistically significant if the margin of error of 1 mm was taken into account. CONCLUSION: A preoperatively normal CHD does not dilate after cholecystectomy and may require further investigation in symptomatic patients.
Assuntos
Colecistectomia , Colelitíase/cirurgia , Ducto Hepático Comum/diagnóstico por imagem , Adulto , Idoso , Colelitíase/diagnóstico por imagem , Colelitíase/patologia , Feminino , Ducto Hepático Comum/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Período Pós-Operatório , Estudos Prospectivos , UltrassonografiaRESUMO
OBJECTIVE: To analyze the cost-effectiveness of resection for liver metastases compared with standard nonsurgical cytotoxic treatment. SUMMARY BACKGROUND DATA: The efficacy of hepatic resection for metastases from colorectal cancer has been debated, despite reported 5-year survival rates of 20% to 40%. Resection is confined to specialized centers and is not widely available, perhaps because of lack of appropriate expertise, resources, or awareness of its efficacy. The cost-effectiveness of resection is important from the perspective of managed care in the United States and for the commissioning of health services in the United Kingdom. METHODS: A simple decision-based model was developed to evaluate the marginal costs and health benefits of hepatic resection. Estimates of resectability for liver metastases were taken from UK-reported case series data. The results of 100 hepatic resections conducted in Sheffield from 1997 to 1999 were used for the cost calculation of liver resection. Survival data from published series of resections were compiled to estimate the incremental cost per life-year gained (LYG) because of the short period of follow-up in the Sheffield series. RESULTS: Hepatic resection for colorectal liver metastases provides an estimated marginal benefit of 1.6 life-years (undiscounted) at a marginal cost of 6,742 pound sterling++. If 17% of patients have only palliative resections, the overall cost per LYG is approximately 5,236 pound sterling (5,985 pound sterling with discounted benefits). If potential benefits are extended to include 20-year survival rates, these figures fall to approximately 1,821 pound sterling (2,793 pound sterling with discounted benefits). Further univariate sensitivity analysis of key model parameters showed the cost per LYG to be consistently less than 15,000 pound sterling. CONCLUSION: In this model, hepatic resection appears highly cost-effective compared with nonsurgical treatments for colorectal-related liver metastases.
Assuntos
Neoplasias Colorretais/patologia , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/cirurgia , Análise de Variância , Antineoplásicos/economia , Análise Custo-Benefício , Técnicas de Apoio para a Decisão , Seguimentos , Custos de Cuidados de Saúde , Humanos , Cuidados Paliativos/economia , Estudos Retrospectivos , Sensibilidade e Especificidade , Análise de SobrevidaRESUMO
BACKGROUND: Chemical ablation of the gallbladder might avoid the need for surgery in elderly, unfit patients. This study examined the efficacy of various chemicals in destroying gallbladder mucosa. METHODS: Ninety-five per cent ethanol, 3 per cent sodium tetradecyl sulphate (STD), trifluoroacetic acid (TFA) 2 mol/l, tetracycline 50 mg/ml, 30 and 50 per cent phenol, and a mucosal exfoliant solution (compound ethylene diamine tetra-acetic acid) were tested for gallbladder ablation in rabbits. Histology was obtained 8 weeks after exposure to these chemicals. RESULTS: Thirty per cent phenol, tetracycline, TFA and ethanol when used as single agents were moderately effective in causing complete gallbladder mucosal obliteration, 50 per cent phenol caused a macroscopic burn of the entire gallbladder. The mucosal exfoliant solution and STD on their own did not cause mucosal destruction but had significantly enhanced efficacy when combined with 95 per cent ethanol, allowing reliable mucosal destruction with a 5-min contact duration. CONCLUSION: Ninety-five per cent ethanol and STD after pretreatment with a mucosal exfoliant solution may be the combination of choice for in situ gallbladder mucosal ablation.
Assuntos
Etanol/farmacologia , Vesícula Biliar/efeitos dos fármacos , Soluções Esclerosantes/farmacologia , Tetradecilsulfato de Sódio/farmacologia , Tetraciclina/farmacologia , Ácido Trifluoracético/farmacologia , Animais , Feminino , Necrose , Projetos Piloto , CoelhosRESUMO
With the advent of 'minimal access' cholecystectomy patients no longer have an exploratory laparotomy at the time of the operation and it is possible that relevant pathology may be missed as a result. This study analyses the findings at exploratory laparotomy in 223 patients undergoing open cholecystectomy. Forty-two patients (19%) were found to have incidental pathology but in only three (1.3%) did this lead to additional operative procedures. We therefore conclude that the loss of exploratory laparotomy at cholecystectomy does not have a significant detrimental effect on patient care.
Assuntos
Colecistectomia , Laparotomia , Adenocarcinoma/diagnóstico , Idoso , Carcinoma/diagnóstico , Divertículo do Colo/diagnóstico , Procedimentos Cirúrgicos Eletivos , Feminino , Humanos , Masculino , Omento , Neoplasias Peritoneais/diagnóstico , Estudos Prospectivos , Neoplasias Gástricas/diagnósticoRESUMO
We have evaluated the value of ultrasonographic measurement of common duct diameter in isolation from other predictors of choledocholithiasis. A cohort of 223 patients who did not have a history of jaundice or pancreatitis and had normal liver function tests underwent pre-operative ultrasound of the common hepatic duct and then had elective (open) cholecystectomy with operative cholangiography. One hundred and ninety-one (86%) of all patients had a normal (< or = 5 mm) common duct and of these only 12 (6%) had common duct calculi. Of the 32 patients who had a common duct diameter greater than 5 mm on pre-operative ultrasonography, 12 (37.5%) patients had ductal calculi. A pre-operatively dilated duct on ultrasonography has a high chance of containing stones and should be considered as a strong indication for pre-operative bile duct imaging or operative cholangiography.
Assuntos
Cálculos Biliares/diagnóstico por imagem , Ducto Hepático Comum/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Colecistectomia , Feminino , Humanos , Cuidados Intraoperatórios , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Estudos Prospectivos , Fatores de Risco , Sensibilidade e Especificidade , UltrassonografiaRESUMO
Fifty patients had residual urine measured by catheterisation immediately before laparoscopic cholecystectomy. The median amount of urine in the bladder was 100 ml (range 5-500 ml). This urine volume does not distend the bladder enough to risk inadvertant perforation during insertion of a subumbilical port. Urinary bladder catheterisation is unnecessary before laparoscopy especially if the bladder is impalpable.